CN111108274B

CN111108274B - Variable nozzle turbocharger

Info

Publication number: CN111108274B
Application number: CN201880058570.2A
Authority: CN
Inventors: 大芦嘉郎
Original assignee: Isuzu Motors Ltd
Current assignee: Isuzu Motors Ltd
Priority date: 2017-09-11
Filing date: 2018-09-05
Publication date: 2022-06-21
Anticipated expiration: 2038-09-05
Also published as: PH12020500455A1; JP7052263B2; JP2019049227A; CN111108274A; WO2019049873A1

Abstract

A variable nozzle turbocharger (1) is provided with: nozzle rings (21), (22) defining a swirl flow path (23); a variable nozzle (30) disposed in the scroll flow path; and a nozzle shaft (40). In a variable nozzle turbocharger in which a nozzle shaft is inserted into a nozzle shaft hole (60) provided in a nozzle ring, the nozzle shaft hole has: a shaft support hole part (61) for supporting the nozzle shaft; and a large diameter hole part (62) which is provided at the end part of the nozzle shaft hole on the spiral flow path side and has a larger diameter than the shaft support hole part (61). The variable nozzle turbocharger is provided with a seal member (50) which is fitted to the nozzle shaft, is housed in the large-diameter hole portion, and seals a gap between an inner circumferential surface (64) of the shaft support hole portion and an outer circumferential surface (43) of the nozzle shaft which faces the inner circumferential surface.

Description

Variable nozzle turbocharger

Technical Field

The present disclosure relates to a variable nozzle turbocharger.

Background

Conventionally, a variable nozzle turbocharger is known as a turbocharger that supercharges intake air by using energy of exhaust gas of an engine (see, for example, patent document 1). Specifically, patent document 1 discloses a variable nozzle turbocharger (variable capacity type supercharger) including: a nozzle ring defining a scroll flow path for introducing exhaust gas of the scroll portion of the turbine into the turbine; a variable nozzle (nozzle vane) disposed in the scroll flow path; and a nozzle shaft as a rotation shaft of the variable nozzle. The nozzle shaft of the variable nozzle is inserted into a nozzle shaft hole provided in the nozzle ring, and is rotatably supported by the nozzle shaft hole.

[ Prior art documents ]

[ patent document ]

Patent document 1: international publication No. 2016/159004

Disclosure of Invention

[ problems to be solved by the invention ]

In the variable nozzle turbocharger as described above, since the diameter of the nozzle shaft hole is larger than the diameter of the nozzle shaft, a gap is formed between the inner circumferential surface of the nozzle shaft hole and the outer circumferential surface of the nozzle shaft facing the inner circumferential surface. Therefore, a part of the exhaust gas of the scroll flow path may leak into the gap. In this case, since the flow rate of the exhaust gas flowing into the turbine decreases, the turbine efficiency of the variable nozzle turbocharger decreases.

The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a variable nozzle turbocharger capable of improving turbine efficiency.

[ means for solving the problems ]

In order to achieve the above object, a variable nozzle turbocharger of the present disclosure includes: a nozzle ring defining a scroll flow path for introducing exhaust gas of the scroll portion of the turbine into the turbine; a variable nozzle disposed in the scroll flow path; and a nozzle shaft as a rotation shaft of the variable nozzle. In the variable nozzle turbocharger in which the nozzle shaft is inserted into a nozzle shaft hole provided in the nozzle ring, the nozzle shaft hole includes: a shaft support hole portion for supporting the nozzle shaft; and a large diameter hole portion provided at an end portion of the nozzle shaft hole on the swirl flow side and having a larger diameter than the shaft support hole portion. The variable nozzle turbocharger includes a seal member that is fitted to the nozzle shaft and is housed in the large diameter hole portion, and that seals a gap between an inner circumferential surface of the shaft support hole portion and an outer circumferential surface of the nozzle shaft that faces the inner circumferential surface.

Effects of the invention

According to the present disclosure, the leakage of the exhaust gas of the scroll flow path into the gap between the inner peripheral surface of the shaft hole portion of the nozzle shaft hole and the outer peripheral surface of the nozzle shaft facing the inner peripheral surface can be suppressed by the seal member housed in the large diameter hole portion of the nozzle ring. Therefore, the turbine efficiency can be improved.

Drawings

Fig. 1 is a schematic cross-sectional view schematically showing the configuration of a variable nozzle turbocharger according to an embodiment.

Fig. 2A is a schematic enlarged cross-sectional view schematically showing a part of the variable nozzle unit of the embodiment enlarged.

Fig. 2B is a schematic enlarged sectional view of the 1 st nozzle ring and the 2 nd nozzle ring in the variable nozzle unit of fig. 2A.

Fig. 2C is a schematic enlarged sectional view of an alternative variable nozzle, a nozzle shaft and a sealing gasket in the variable nozzle unit of fig. 2A.

Fig. 3A is a schematic enlarged cross-sectional view schematically showing a partially enlarged variable nozzle unit according to a modification of the embodiment.

Fig. 3B is a schematic enlarged sectional view of the 1 st nozzle ring and the 2 nd nozzle ring of the variable nozzle unit of fig. 3A.

Fig. 3C is a schematic enlarged sectional view of an alternative variable nozzle, a nozzle shaft and a sealing gasket in the variable nozzle unit of fig. 3A.

Fig. 3D is a schematic perspective view of a sealing gasket.

Detailed Description

(embodiment mode)

Hereinafter, the variable nozzle turbocharger 1 according to the embodiment will be described with reference to the drawings. In addition, the drawings are schematically illustrated to facilitate understanding of the configuration, and the dimensions of the respective portions in the drawings do not necessarily coincide with those of the actual object. Fig. 1 is a schematic cross-sectional view schematically showing the structure of a variable nozzle turbocharger 1 according to the present embodiment. Fig. 1 schematically illustrates a cross-sectional view of one side of a turbine axis 6 (which is an axis of a turbine shaft 4 described later) in the variable nozzle turbocharger 1. In addition, in FIG. 1, orthogonal coordinates of X-Y-Z are provided for reference. The Y-axis is a shaft parallel to the turbine axis 6.

The variable nozzle turbocharger 1 is connected to an engine of a vehicle via a pipe such as an exhaust pipe or an intake pipe. As an example of this engine, a diesel engine is used in the present embodiment. The variable nozzle turbocharger 1 includes: a turbine 2, a compressor 3, a turbine shaft 4, a turbine bearing 5, a turbine housing 7, a compressor housing 8, a bearing housing 9, and a variable nozzle unit 20.

The turbine 2 and the compressor 3 are connected by a turbine shaft 4. The turbine 2 is constituted by a turbine wheel having a plurality of turbine blades. The compressor 3 is constituted by a compressor wheel having a plurality of compressor blades. The turbine bearing 5 is a bearing for axially supporting the turbine shaft 4, and is housed in a bearing housing 9.

The turbine housing 7 houses the turbine 2 therein. The compressor housing 8 houses the compressor 3 therein. The turbine housing 7 is provided with a turbine scroll portion 10 and an exhaust outlet 11. The compressor housing 8 is provided with an intake inlet 12 and a compressor scroll portion 13. The exhaust gas (E) discharged from the engine flows into the turbine scroll portion 10, then contacts the turbine 2, and is discharged from the exhaust gas outlet 11. The intake air (a) flows into the intake air inlet 12 of the compressor housing 8 on the upstream side of the variable nozzle turbocharger 1.

The turbine 2 receives energy of the exhaust gas flowing in from the turbine scroll portion 10, and rotates about the turbine axis 6 as a rotation center. When the turbine 2 rotates, the compressor 3 connected to the turbine 2 via the turbine shaft 4 also rotates. The compressor 3 supercharges intake air by rotation of the compressor 3. The supercharged intake air is discharged from the compressor turbine portion 13 and supplied to the engine. In this manner, the variable nozzle turbocharger 1 supercharges intake air using the energy of exhaust gas.

Next, the variable nozzle unit 20 is explained. Fig. 2A is a schematic enlarged sectional view schematically showing a part of the variable nozzle unit 20 of the variable nozzle turbocharger 1 in an enlarged manner. Referring to fig. 1 and 2A, the variable nozzle unit 20 includes a pair of nozzle rings (a 1 st nozzle ring 21 and a 2 nd nozzle ring 22), a variable nozzle 30, a nozzle shaft 40, a variable nozzle driving mechanism 80, and a seal gasket 50 as one example of a seal member.

The 1 st nozzle ring 21 and the 2 nd nozzle ring 22 are each formed of an annular member having a turbine axis 6 as a center axis. Specifically, the 1 st nozzle ring 21 and the 2 nd nozzle ring 22 are formed of annular members surrounding the periphery of the turbine 2.

Between an opposing face of the 1 st nozzle ring 21 opposing the 2 nd nozzle ring 22 and an opposing face of the 2 nd nozzle ring 22 opposing the 1 st nozzle ring 21, a scroll flow path 23 is defined. The scroll flow path 23 is an internal exhaust flow path for introducing the exhaust gas of the turbine scroll portion 10 into the turbine 2.

The variable nozzle 30 is disposed in the turbine scroll portion 10. Note that, in fig. 1 and fig. 2A to 2C, only 1 variable nozzle 30 is illustrated, but actually, the variable nozzle unit 20 includes a plurality of variable nozzles 30. Specifically, the variable nozzle 30 is arranged in a plurality of circumferential rows with the turbine axis 6 as the center axis, with a predetermined interval between the variable nozzle 30 and the adjacent variable nozzle 30.

The nozzle shaft 40 is a rotation shaft of the variable nozzle 30. In fig. 2A, a nozzle axis 41 as an axis of the nozzle shaft 40 is illustrated. Each variable nozzle 30 rotates about a nozzle axis 41 as a rotation center. The nozzle axis 41 of the present embodiment is an axis parallel to the Y axis of the orthogonal coordinate of X-Y-Z.

Referring to fig. 1, the variable nozzle driving mechanism 80 is a rotation driving mechanism for rotating the variable nozzle 30 (in fig. 1, illustration of each component of the variable nozzle driving mechanism 80 is omitted). The variable nozzle driving mechanism 80 is disposed in the variable nozzle driving chamber 14 provided in the bearing housing 9. The variable nozzle driving mechanism 80 is connected to an end (end on the Y direction side) of the nozzle shaft 40 on the opposite side to the scroll flow path 23 side, and rotates the variable nozzle 30 by rotating the nozzle shaft 40. Note that, as the variable nozzle driving mechanism 80, for example, a known variable nozzle driving mechanism used in a known variable nozzle turbocharger as exemplified in patent document 1 can be used, and therefore, a detailed description thereof will be omitted.

By rotating each variable nozzle 30 by the variable nozzle driving mechanism 80, the interval between the mutually adjacent variable nozzles 30 (this interval is generally referred to as a blade interval) is changed. When the blade interval is narrowed, the exhaust gas in the scroll passage 23 is throttled, and therefore the flow rate of the exhaust gas flowing into the turbine 2 through the scroll passage 23 is increased. As a result, the rotational speed of the turbine 2 can be increased. In this way, the variable nozzle turbocharger 1 can adjust the rotation speed of the turbine 2 by adjusting the rotation angle of the variable nozzle 30.

Fig. 2B is a schematic enlarged sectional view of the 1 st nozzle ring 21 and the 2 nd nozzle ring 22 of the variable nozzle unit 20 of fig. 2A. Fig. 2C is a schematic enlarged sectional view taken of the variable nozzle 30, the nozzle shaft 40 and the sealing washer 50 in the variable nozzle unit 20 of fig. 2A.

As shown in fig. 2A and 2C, the nozzle shaft 40 of the present embodiment is formed of a shaft body 42 having the same outer diameter. Further, a gasket 50 (i.e., a seal member) is fitted to the shaft body portion 42 of the nozzle shaft 40. Specifically, the gasket 50 of the present embodiment is formed of a flat plate-shaped ring member. An inner peripheral hole 52 (a hole on the inner peripheral side of the ring) of the gasket 50 is fitted to the outer peripheral surface 43 of the shaft body 42.

As shown in fig. 2B, the 1 st nozzle ring 21 is provided with a nozzle shaft hole 60. The nozzle shaft hole 60 of the present embodiment is formed by a through hole penetrating in the direction of the nozzle axis 41 (the direction along the Y axis). The nozzle shaft 40 is inserted into the nozzle shaft hole 60.

Specifically, the nozzle shaft hole 60 includes: a shaft support hole 61 for rotatably supporting the nozzle shaft 40; the large diameter hole part 62 has a larger diameter than the shaft support hole part 61. The large-diameter hole 62 is provided at an end of the nozzle shaft hole 60 on the scroll flow path 23 side (an end of the nozzle shaft hole 60 on the-Y direction side). The shaft support hole 61 is connected to the Y-direction side end of the large diameter hole 62. Thus, the nozzle shaft hole 60 has a stepped portion 63 at a boundary portion between the large diameter hole 62 and the shaft support hole 61.

The diameter of the shaft support hole 61 is set to be slightly larger than the diameter of the shaft main body 42 of the nozzle shaft 40. Thus, when the nozzle shaft 40 rotates, the outer peripheral surface 43 of the shaft body portion 42 of the nozzle shaft 40 rotates while sliding on the inner peripheral surface 64 of the shaft support hole portion 61.

The diameter of the large-diameter hole 62 is set larger than the outer diameter of the seal washer 50. The seal ring 50 fitted to the nozzle shaft 40 is accommodated in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23. Specifically, the thickness of the gasket 50 (the length in the direction of the nozzle axis 41) in the present embodiment is set to be equal to or less than the thickness of the large-diameter hole portion 62, and thus the-Y direction side end surface of the gasket 50 is set so as not to protrude into the scroll flow path 23 (in other words, so as not to protrude further in the-Y direction than the-Y direction side end surface of the 1 st nozzle ring 21).

The gasket 50 accommodated in the large-diameter hole 62 seals a gap between the inner circumferential surface 64 of the shaft support hole 61 of the nozzle shaft hole 60 and the outer circumferential surface 43 of the nozzle shaft 40 facing the inner circumferential surface 64.

Specifically, in the present embodiment, the gap between the inner peripheral hole 52 of the gasket 50 and the outer peripheral surface 43 of the shaft body 42 of the nozzle shaft 40 is set to be small so that the exhaust gas from the scroll flow path 23 is unlikely to pass through the gap. Therefore, the exhaust gas of the scroll flow path 23 is suppressed from leaking through the clearance into the clearance between the inner peripheral surface 64 of the shaft support hole portion 61 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64 by the labyrinth effect produced by the clearance.

Further, when the gasket 50 is pressed in the Y direction by the pressure of the exhaust gas of the scroll flow path 23, the gasket 50 contacts the step 63 of the nozzle shaft hole 60. Thus, the gap between the sealing gasket 50 and the stepped portion 63 is substantially zero. Further, the gap between the inner peripheral surface 65 of the large-diameter hole portion 62 and the outer peripheral surface 51 of the gasket 50 is set to be small, so that the exhaust gas of the scroll flow path 23 is hard to flow into the gap. Therefore, the labyrinth effect produced by these clearances suppresses leakage of the exhaust gas of the scroll flow path 23 into the clearance between the inner peripheral surface 64 of the shaft support hole 61 and the outer peripheral surface 43 of the shaft main body portion 42 of the nozzle shaft 40 facing the inner peripheral surface 64, through the clearance between the inner peripheral surface 65 of the large-diameter hole portion 62 and the outer peripheral surface 51 of the gasket 50 and the clearance between the gasket 50 and the stepped portion 63.

That is, according to the present embodiment, the exhaust gas of the scroll flow path 23 is suppressed from leaking into the gap between the inner peripheral surface 64 of the shaft support hole portion 61 of the nozzle shaft hole 60 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64 by forming the labyrinth structure by the gasket 50 accommodated in the large diameter hole portion 62.

As shown in fig. 2A and 2C, the shaft body 42 of the nozzle shaft 40 of the present embodiment is configured to protrude further in the-Y direction than the variable nozzle 30. Therefore, as shown in fig. 2B, the 2 nd nozzle ring 22 of the present embodiment is formed with a nozzle shaft hole 70 into which a portion projecting in the-Y direction from the variable nozzle 30 of the shaft body portion 42 is inserted. If the shaft body 42 is configured to have no portion projecting in the-Y direction from the variable nozzle 30, the nozzle shaft hole 70 of the 2 nd nozzle ring 22 is not necessary.

Next, the operation and effect of the present embodiment will be described. First, as a comparative example, a variable nozzle turbocharger without the gasket 50 and the large diameter hole portion 62 is assumed. In the case of the variable nozzle turbocharger of this comparative example, a part of the exhaust gas of the scroll flow path may leak into a gap between the inner peripheral surface of the shaft support hole portion of the nozzle shaft hole and the outer peripheral surface of the nozzle shaft opposed to the inner peripheral surface. In this case, since the flow rate of the exhaust gas flowing into the turbine decreases by the amount of the leaked exhaust gas, the turbine efficiency of the variable nozzle turbocharger decreases. Specifically, in the case of the comparative example, the turbine efficiency is reduced particularly in the low speed region.

In contrast, according to the variable nozzle turbocharger 1 of the present embodiment, the exhaust gas of the scroll flow path 23 can be suppressed from leaking into the gap between the inner peripheral surface 64 of the shaft support hole portion 61 of the nozzle shaft hole 60 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64 by the seal ring 50 housed in the large diameter hole portion 62. Further, since the gasket 50 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23, the gasket 50 protruding into the scroll flow path 23 also suppresses the flow of the exhaust gas in the scroll flow path 23 from being obstructed. Therefore, according to the present embodiment, the turbine efficiency can be improved. In particular, the turbine efficiency in the low speed region can be improved.

In the present embodiment, the gasket 50 is housed in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23, but the present invention is not limited to this configuration. The sealing gasket 50 may also be made to partially protrude to the swirling flow path 23. In this case, the exhaust gas of the scroll flow path 23 can be prevented from leaking into the gap between the inner peripheral surface 64 of the shaft support hole portion 61 of the nozzle shaft hole 60 and the outer peripheral surface 43 of the nozzle shaft 40 facing the inner peripheral surface 64 by the sealing function of the gasket 50. However, when the gasket 50 is accommodated in the large-diameter hole portion 62 so as not to protrude into the scroll flow path 23 as in the present embodiment, the turbine efficiency can be effectively improved in that the gasket 50 protruding into the scroll flow path 23 can suppress the obstruction of the flow of the exhaust gas in the scroll flow path 23. In this regard, it is preferable that the seal gasket 50 does not protrude into the scroll flow path 23.

(modification of embodiment)

Next, a variable nozzle turbocharger 1a according to a modification of the above embodiment will be described. The variable nozzle turbocharger 1a of the present modification differs from the variable nozzle turbocharger 1 of the above-described embodiment in that the variable nozzle unit 20a is included instead of the variable nozzle unit 20. Fig. 3A is a schematic enlarged cross-sectional view schematically showing a partially enlarged variable nozzle unit 20a of the present modification. Fig. 3B is a schematic enlarged sectional view of the 1 st nozzle ring 21 and the 2 nd nozzle ring 22 of the variable nozzle unit 20a of fig. 3A. Fig. 3C is a schematic enlarged sectional view of the variable nozzle 30, the nozzle shaft 40 and the sealing washer 50a of the variable nozzle unit 20a of fig. 3A. Fig. 3D is a schematic perspective view of the sealing gasket 50 a.

The variable nozzle unit 20a of the present modification differs from the variable nozzle unit 20 of the above-described embodiment in that a seal gasket 50a is included instead of the seal gasket 50 as an example of a seal member. The gasket 50a is a gasket that generates a force opposing a compressive force when the compressive force is applied to the gasket 50a in the thickness direction.

The specific shape of the gasket 50a is not particularly limited if the gasket has such a function, but the gasket 50a of the present modification is configured by a conical disc spring type gasket in which the radial center portion of the gasket 50a protrudes to one side (specifically, the-Y direction side) with respect to the outer peripheral portion of the gasket 50a, as an example (see fig. 3C and 3D). In this case, in the case where a compressive force is applied to the thickness direction (direction along the Y-axis) of the seal gasket 50a, the seal gasket 50a generates a force (specifically, a spring force) that opposes the compressive force.

According to this modification, in addition to the operational effects of the above embodiment, the following operational effects can be exhibited. Specifically, when the compression force is applied to the gasket 50a by the pressure of the exhaust gas of the scroll flow path 23, the fitting degree between the inner peripheral hole 52 of the gasket 50a and the nozzle shaft 40 can be increased, and the fitting degree between the outer peripheral edge 53 of the gasket 50a and the step 63 of the nozzle shaft hole 60 can be increased. This effectively suppresses passage of the exhaust gas of the scroll flow path 23 through the gap between the inner peripheral hole 52 of the gasket 50a and the nozzle shaft 40 and the gap between the outer peripheral edge 53 of the gasket 50a and the step 63 of the nozzle shaft hole 60. As a result, the exhaust gas of the scroll flow path 23 can be effectively prevented from leaking into the gap between the inner circumferential surface 64 of the shaft support hole 61 and the outer circumferential surface 43 of the nozzle shaft 40 facing the inner circumferential surface 64, and therefore, the reduction in turbine efficiency can be effectively prevented.

When the gasket 50a is assembled to the nozzle shaft 40 and the large-diameter hole 62 (i.e., in the manufacturing process), it is preferable that the gasket is assembled in a state where a predetermined amount of compressive force is applied in the thickness direction. In this case, if a portion (for example, a groove) for catching the inner peripheral hole 52 of the gasket 50a is formed in the outer peripheral surface 43 of the nozzle shaft 40, the nozzle shaft 40 and the large-diameter hole portion 62 are preferably easily assembled while applying a compressive force to the gasket 50 a.

As described above, since the spring force of the gasket 50a can be constantly generated by assembling the gasket 50a to the nozzle shaft 40 and the large diameter hole part 62 in a state where the compressive force is applied to the gasket 50a, the fitting degree of the inner circumferential hole 52 of the gasket 50a and the nozzle shaft 40 can be improved, and the fitting degree of the outer circumferential edge 53 of the gasket 50a and the step part 63 of the nozzle shaft hole 60 can be improved. As a result, leakage of the exhaust gas from the scroll flow path 23 can be effectively suppressed, and therefore, a decrease in turbine efficiency can be effectively suppressed.

Further, by assembling the gasket 50a to the nozzle shaft 40 and the large-diameter hole portion 62 in a state where the compressive force is applied to the gasket 50a as described above, even when pressure pulsation (pressure fluctuation) occurs in the exhaust gas of the scroll passage 23, it is possible to effectively suppress displacement of the gasket 50a in the-Y direction (floating of the gasket 50 a) due to the pressure pulsation and separation of the outer peripheral edge 53 of the gasket 50a from the step portion 63. In this regard, the decrease in turbine efficiency can also be effectively suppressed.

While the preferred embodiments of the present disclosure have been described above, the present disclosure is not limited to the specific embodiments, and various modifications and changes can be made within the scope of the present disclosure described in the claims.

The present application is based on the japanese patent application filed on 9/11/2017 (japanese application 2017-173695), the contents of which are hereby incorporated by reference.

[ Industrial availability ]

The variable nozzle turbocharger of the present disclosure is useful in that it can improve turbine efficiency.

[ description of reference numerals ]

1. 1a variable nozzle turbocharger

2 turbine

3 compressor

10 turbine volute section

20. 20a variable nozzle unit

21 st nozzle ring

22 nd 2 nozzle ring

23 swirl flow path

30 variable nozzle

40 nozzle shaft

42 shaft body part

43 outer peripheral surface

50. 50a sealing gasket (sealing member)

60 nozzle shaft hole

61 axle support hole part

62 big-diameter hole part

63 step part

64 inner peripheral surface

Claims

1. A variable nozzle turbocharger comprising: a nozzle ring defining a scroll flow path for introducing exhaust gas of the scroll portion of the turbine into the turbine; a variable nozzle disposed in the scroll flow path; and a nozzle shaft as a rotation shaft of the variable nozzle; the nozzle shaft is inserted into a nozzle shaft hole arranged on the nozzle ring, wherein,

the nozzle shaft hole has a shaft support hole portion for supporting the nozzle shaft by a shaft and a large diameter hole portion which is provided at an end portion of the nozzle shaft hole on the swirl flow side and has a larger diameter than the shaft support hole portion;

the variable nozzle turbocharger includes a seal member that is fitted to the nozzle shaft and is housed in the large diameter hole portion, and that seals a gap between an inner circumferential surface of the shaft support hole portion and an outer circumferential surface of the nozzle shaft facing the inner circumferential surface,

the sealing member is a sealing member that generates a force opposing a compressive force when the compressive force is applied to the sealing member in a thickness direction thereof,

the seal member is composed of a conical disc spring-type seal gasket, the radial center part of the seal gasket protrudes to one side relative to the outer periphery part of the seal gasket,

a groove for clamping the inner circumference hole of the sealing washer is formed on the outer circumference surface of the nozzle shaft,

the inner circumferential hole catches the groove to be assembled in a state where the sealing gasket is applied with a compression force compressing it by a predetermined amount in a thickness direction.

2. The variable nozzle turbocharger as in claim 1,

the seal member is housed in the large-diameter hole portion so as not to protrude into the scroll flow path.

3. The variable nozzle turbocharger according to claim 1 or 2,

the nozzle ring is provided with a 1 st nozzle ring and a 2 nd nozzle ring;

the scroll flow path is defined between an opposing face of the 1 st nozzle ring opposing the 2 nd nozzle ring and an opposing face of the 2 nd nozzle ring opposing the 1 st nozzle ring.